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x86/xen: Support objtool validation in xen-asm.S

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The OBJECT_FILES_NON_STANDARD annotation is used to tell objtool to
ignore a file.  File-level ignores won't work when validating vmlinux.o.

Tweak the ELF metadata and unwind hints to allow objtool to follow the
code.

Cc: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8b042a09c69e8645f3b133ef6653ba28f896807d.1611263462.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2021-01-21 15:29:28 -06:00
parent c26acfbbfb
commit cde07a4e44
2 changed files with 19 additions and 11 deletions
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1
arch/x86/xen/Makefile
View File

@ -1,5 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
OBJECT_FILES_NON_STANDARD_xen-asm.o := y
ifdef CONFIG_FUNCTION_TRACER
# Do not profile debug and lowlevel utilities

29
arch/x86/xen/xen-asm.S
View File

@ -14,6 +14,7 @@
#include <asm/thread_info.h>
#include <asm/asm.h>
#include <asm/frame.h>
#include <asm/unwind_hints.h>
#include <xen/interface/xen.h>
@ -146,6 +147,7 @@ SYM_FUNC_END(xen_read_cr2_direct);
.macro xen_pv_trap name
SYM_CODE_START(xen_\name)
UNWIND_HINT_EMPTY
pop %rcx
pop %r11
jmp \name
@ -184,6 +186,7 @@ xen_pv_trap asm_exc_xen_hypervisor_callback
SYM_CODE_START(xen_early_idt_handler_array)
i = 0
.rept NUM_EXCEPTION_VECTORS
UNWIND_HINT_EMPTY
pop %rcx
pop %r11
jmp early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE
@ -210,11 +213,13 @@ hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
* rsp->rax }
*/
SYM_CODE_START(xen_iret)
UNWIND_HINT_EMPTY
pushq $0
jmp hypercall_iret
SYM_CODE_END(xen_iret)
SYM_CODE_START(xen_sysret64)
UNWIND_HINT_EMPTY
/*
* We're already on the usermode stack at this point, but
* still with the kernel gs, so we can easily switch back.
@ -250,7 +255,8 @@ SYM_CODE_END(xen_sysret64)
*/
/* Normal 64-bit system call target */
SYM_FUNC_START(xen_syscall_target)
SYM_CODE_START(xen_syscall_target)
UNWIND_HINT_EMPTY
popq %rcx
popq %r11
@ -263,12 +269,13 @@ SYM_FUNC_START(xen_syscall_target)
movq $__USER_CS, 1*8(%rsp)
jmp entry_SYSCALL_64_after_hwframe
SYM_FUNC_END(xen_syscall_target)
SYM_CODE_END(xen_syscall_target)
#ifdef CONFIG_IA32_EMULATION
/* 32-bit compat syscall target */
SYM_FUNC_START(xen_syscall32_target)
SYM_CODE_START(xen_syscall32_target)
UNWIND_HINT_EMPTY
popq %rcx
popq %r11
@ -281,10 +288,11 @@ SYM_FUNC_START(xen_syscall32_target)
movq $__USER32_CS, 1*8(%rsp)
jmp entry_SYSCALL_compat_after_hwframe
SYM_FUNC_END(xen_syscall32_target)
SYM_CODE_END(xen_syscall32_target)
/* 32-bit compat sysenter target */
SYM_FUNC_START(xen_sysenter_target)
SYM_CODE_START(xen_sysenter_target)
UNWIND_HINT_EMPTY
/*
* NB: Xen is polite and clears TF from EFLAGS for us. This means
* that we don't need to guard against single step exceptions here.
@ -301,17 +309,18 @@ SYM_FUNC_START(xen_sysenter_target)
movq $__USER32_CS, 1*8(%rsp)
jmp entry_SYSENTER_compat_after_hwframe
SYM_FUNC_END(xen_sysenter_target)
SYM_CODE_END(xen_sysenter_target)
#else /* !CONFIG_IA32_EMULATION */
SYM_FUNC_START_ALIAS(xen_syscall32_target)
SYM_FUNC_START(xen_sysenter_target)
SYM_CODE_START(xen_syscall32_target)
SYM_CODE_START(xen_sysenter_target)
UNWIND_HINT_EMPTY
lea 16(%rsp), %rsp /* strip %rcx, %r11 */
mov $-ENOSYS, %rax
pushq $0
jmp hypercall_iret
SYM_FUNC_END(xen_sysenter_target)
SYM_FUNC_END_ALIAS(xen_syscall32_target)
SYM_CODE_END(xen_sysenter_target)
SYM_CODE_END(xen_syscall32_target)
#endif /* CONFIG_IA32_EMULATION */